Traditional three piece railway freight car trucks are comprised of three basic structural components. These components are two laterally spaced sideframes receiving a bolster extending laterally between the two sideframes. Each sideframe has a central pocket including a bottom support member. A spring group is received on the bottom support member to in turn support the end of the bolster. Snubbing devices such as friction shoes are located between the interface of the sideframe and the sloped faces of the bolster ends to provide damping for oscillations of the spring group. A typical three piece freight car truck with spring groups is shown in U.S. Pat. Nos. 5,524,551 and 5,791,258.
The spring group itself can comprise up to thirteen or more springs each of which is either of a traditional steel coil construction or of a shock absorber type construction. There is a desire among rail freight car builders and operators to decrease the weight of such freight cars to allow a greater weight of material to be hauled.
Accordingly, it is an object of the present invention to improve the spring group interface between the bolster and the sideframe in a railway freight car truck.